1. Field of the Invention
This invention relates to an electrophotographic image forming method, an electrophotographic image forming apparatus, a processing cartridge and an electrophotographic photoreceptor, particularly relates to an electrophotographic image forming method and an electrophotographic image forming apparatus having a process for cleaning a toner remained on an organic photoreceptor by a brush roller and an elastic rubber blade while the photoreceptor is moving, and a processing cartridge and an electrophotographic photoreceptor to be used in the apparatus.
2. Background of the Invention
Recently, an organic photoreceptor containing an organic photoconductive substance is most widely used for the electrophotographic photoreceptor. The organic photoreceptor has advantages such that the material responding to various exposure light sources from visible light to infrared light can be easily developed, a material without environmental pollution can be selected and the production cost is low, compared with another photoreceptor. However, only a drawback of the organic photoreceptor is weak in the mechanical strength and the surface of the photoreceptor is deteriorated or damaged for a lot of copying or printing.
Generally, in the electrophotographic copying apparatus according to Carlson method, a photoreceptor is uniformly charged and the charge is imagewise eliminated by light exposure to form a static latent image. The static latent image is visualized by developing by a toner, and the toner is transferred to paper and fixed.
However, the toner on the photoreceptor is not all transferred and a part of the toner is remained on the photoreceptor. When the image formation process is repeated under such the condition, a high quality copied image without any contamination cannot be obtained since the latent image formation is disturbed by the influence of the remained toner. Accordingly, it is necessary to remove the remained toner. A fur brush roller, a magnetic brush roller or a blade is usually used for the cleaning means, and the blade is mainly used from the viewpoint of the performance and the structure thereof. A plate of rubber elastic material is usually used for the material of the blade.
As above-mentioned, an electrical and mechanical force are directly applied to the surface of the photoreceptor by the charging means, the developing means, the transferring means and the cleaning means. Accordingly, a high resistivity to such the forces is required to the photoreceptor. Particularly, a high resistivity to the wear or scratch formation of the surface of the photoreceptor caused by the friction, and a high mechanical durability to peel of the layer caused by an impact by intruding a foreign substance or removing a jammed paper are required. Specifically, the durability to the damage and peel of the layer the same as that of an inorganic photoreceptor is strongly demanded.
Until now, various investigations have been performed to satisfy the requirements as above-mentioned.
It has been reported regarding the mechanical durability, that the wearing property of the surface and the toner filming resistivity can be improved by using a bisphenol Z type polycarbonate resin as the binder at the surface of the organic photoreceptor. Japanese Patent Publication Open to Public Inspection (JP O.P.I.) No. 6-118681 discloses the use of a colloidal silica-containing hardenable silicone resin as the surface of the photoreceptor.
However, the photoreceptor using the bisphenol Z type polycarbonate resin is insufficient in the resistivity to the wearing and not has the sufficient durability. Besides, the surface layer of the colloidal silica-containing hardenable silicone resin is superior in the strength and is widely studied for the means for raising the anti-wearing property and the anti-scratch property which are the drawback of the OPC. However, a problem of the electricity property under a low humidity is raised when the siloxane resin is used in the surface layer. Although it has been tried for improve such the problem to reduce the surface electric conductivity by an addition of an electroconductive particle, a problem of occurring an image flowing under a high temperature and a high humidity has been raised. The inventors have found that the electricity property under a condition low temperature and low humidity can be improved by combining a charge transportable structural unit into the siloxane resin (Japanese Patent Application No. 11-70380).
However, a problem that the image quality is deteriorated by an accumulated adhered matter since an adhered matter caused by toner and paper powder on the surface of the photoreceptor are become to be difficultly removed accompanied with the raising the strength of the surface, hitherto the matter adhered on the surface is removed by the wearing of the surface.
The object of the invention is to provide an electrophotographic image forming method, an electrophotographic image forming apparatus, and a processing cartridge and an electrophotographic photoreceptor to be used therein, by which an electrophotographic image with a high image quality can be stably obtained for a long period.
As a result of the earnest investigation for the dissolution of the problem mentioned above by the inventors, it is found that the object of the invention can be attained by cleaning an electrophotographic photoreceptor containing a siloxane resin having an electric charge transportable structural unit and a cross-linked structure by a cleaning means having both of an elastic rubber blade and a brush roller. The inventors have found that the object of the invention is attained by the followings.
1. An electrophotographic image forming method comprising the step of cleaning a toner remained on an electrophotographic photoreceptor by a brush roller and an elastic rubber blade after transferring a toner image formed on the electrophotographic photoreceptor to an image receiving material wherein the photoreceptor has a resin layer comprising a siloxane resin having an electric charge transportable structural unit and a cross-linked structure, the thickness of the single filament and the density of the filament of the brush roller are each from 6 denier to 30 denier and from 4.5xc3x97102 to 15.5xc3x97102 f/cm2 (number of filament per square centimeter),respectively, and the pressure of the elastic rubber blade to the photoreceptor surface is from 5 to 30 g/cm.
2. An electrophotographic image forming method comprising the step of cleaning a toner remained on an electrophotographic photoreceptor by a brush roller and an elastic rubber blade after transferring a toner image formed on the electrophotographic photoreceptor to an image receiving material wherein the photoreceptor has a resin layer comprising a siloxane resin having an electric charge transportable structural unit and a cross-linked structure, wherein the toner is cleaned by a brush roller touched to the photoreceptor under a condition of an effective driving torque of from 0.1 kgfxc2x7cm to 2.0 kgfxc2x7cm and an elastic rubber blade touched to the photoreceptor surface with a pressure of from 5 to 30 g/cm.
Effective driving torque: T=T1xe2x88x92T2
T1: The driving torque of the brush roller when of the brush roller is touched to the photoreceptor
T2: The driving torque of the brush roller when of the brush roller is not touched to the photoreceptor
3. The electrophotographic image forming method as described in items 1 and 2 mentioned above, wherein the electric charge transportable structural unit having the following structure is in the structure of the siloxane resin. 
wherein X is a structural unit having an electric charge transport ability and bonded with Y through a carbon atom or a silicon atom constituting the structural unit, Y is a group of two or more atoms or groups without the adjacent bonding atom (Si and C).
4. The electrophotographic image forming method as described in items 1 to 3 mentioned above, wherein Y is an oxygen atom, sulfur atom or an NR group.
R is a hydrogen atom or a monovalent organic group.
5. The electrophotographic image forming method as described in items 1 to 4 mentioned above, wherein the resin layer is a layer containing a siloxane resin having a cross-linked structure and a structural unit having an electric charge transport ability which is obtained by reacting an organic silicon compound having a hydroxyl group or a hydrolyzable group with an electric charge transportable compound having a hydroxyl group.
6. The electrophotographic image forming method as described in items 1 to 5 mentioned above, wherein the resin layer contains an organic fine particle having an average particle diameter of from 0.05 xcexcm to 10 xcexcm.
7. The electrophotographic image forming method as described in item 6 mentioned above, wherein the organic fine particle is a fine particle of resin containing a fluorine atom.
8. The electrophotographic image forming method as described in items 1 to 7 mentioned above, wherein the resin layer contains colloidal silica.
9. An electrophotographic image forming apparatus having a cleaning means for removing a toner remained on the electrophotographic photoreceptor thereof for repeatedly forming images wherein the photoreceptor comprises a siloxane resin containing a structural unit having an electric charge transport ability and a cross-linked structure, and the toner remained on the photoreceptor is removed by a brush roller having a thickness of single filament of from 6 to 30 denier and the density of the filament of from 4.5xc3x97102 to 15.5 f/cm2 (number of filament per square centimeter) and an elastic rubber blade pressed to the surface of the photoreceptor with a pressure of from 5 to 30 g/cm.
10. An electrophotographic image forming apparatus having a cleaning means for removing a toner remained on the electrophotographic photoreceptor thereof for repeatedly forming images wherein the photoreceptor comprises a siloxane resin containing a structural unit having an electric charge transport ability and a cross-linked structure, and the toner remained on the photoreceptor is removed by a brush roller touched to the photoreceptor under a condition of an effective driving torque of from 0.1 kgfxc2x7cm to 2.0 kgfxc2x7cm and an elastic rubber blade pressed to the surface of the photoreceptor with a pressure of from 5 to 30 g/cm.
Effective driving torque: T=T1xe2x88x92T2
T1: The driving torque of the brush roller when of the brush roller is touched to the photoreceptor
T2: The driving torque of the brush roller when of the brush roller is not touched the photoreceptor
11. A processing cartridge to be used in an electrophotographic image forming apparatus having a cleaning means for removing a toner remained on the electrophotographic photoreceptor thereof, in which the photographic photoreceptor having a resin layer comprising a siloxane resin having a structural unit having an electric charge transport ability and a cross-linked structure, and a cleaning means including a brush roller having a filament having a single filament thickness of from 6 to 30 denier and a filament density of 4.5xc3x97102 to 15.5 f/cm2 (filament number per square centimeter) and an elastic rubber blade touched to the photoreceptor surface with a pressure of from 5 to 30 g/cm, are built up to one unit designed so as to be capable of putting onto and taking off from the apparatus.
12. The photoreceptor comprising a resin layer which comprises a structural unit having charge transferable characteristics, siloxane based resin having cross-linking structure, organic particles having an average particle size of 0.05 to 10 xcexcm and an antioxidation agent.